Germination of Pinus maximartinezii seeds from two relict populations: effects of morphological attributes, seed origin, and pre-germination treatments

Abstract Pinus maximartinezii is an endemic and endangered Mexican pinyon pine highly restricted, only two relict populations are currently known. Effective conservation of this species requires the development of reliable seedling propagation protocols, but germination of P. maximartinezii seeds is problematic, likely due to water-impermeable seed coats. Methods to enhance germination are therefore necessary, yet this aspect remains poorly understood and understudied. This study aimed to evaluate the effects of mechanical and chemical scarification treatments on seed germination, linking treatment effectiveness with seed morphological traits and origin to identify, in turn, the influence of these factors. Provenances differed in seed size and seed coat thickness, thereby affecting water imbibition and germination dynamics. Seeds from Juchipila (Zacatecas) had thinner seed coats (1.4 mm) and imbibed water more rapidly (0.10 g H 2 O g –1 h –1 ), and germinated readily without any treatment (71.7%). In contrast, seeds from La Muralla (Durango) had slightly thicker coats (1.5 mm), imbibed more slowly (0.07 g H 2 O g –1 h –1 ) and required scarification to improve their relative low germination percentage (59.1%). Findings highlight the relevance of seed morphological traits and origin in defining effective pre-germination protocols for P. maximartinezii .